defxmlSpacePreserve: PrefixedAttribute

Attribute tag that PrettyPrinter won't ignore, saying "don't mess with my spaces"
Without this, PrettyPrinter will flatten multiple entries for ExtraDependencyAttributes and make them
unparseable.

Attribute tag that PrettyPrinter won't ignore, saying "don't mess with my spaces"
Without this, PrettyPrinter will flatten multiple entries for ExtraDependencyAttributes and make them
unparseable. (e.g. a plugin that depends on multiple plugins will fail)